Wireless communication in a knowledge information era is expected to be developed from a second generation wireless communication based on sound and text, and a third generation mobile communication of image information transmission (IMT2000), to a fourth generation system having a transmission speed larger than 100 Mbps. The fourth generation system having such a broad bandwidth requires use of a new frequency in place of a conventional frequency, as the conventional frequency bandwidth has already become saturated, and it is very important to use a millimeter wave bandwidth as the frequency to realize such a broad bandwidth and high-speed communication.
However, the communication system of a millimeter wave bandwidth is expensive and bulky as a result of being constructed with a plurality of individual devices, which are the shortcomings in commercializing this bandwidth. In order to overcome these shortcomings and to use millimeter wave RF components, many studies have been developed for the miniaturization of the devices, devices having a low cost and a low loss, and a related packaging technology.
Particularly, in case that a System in a Package (SiP) technology employs a low temperature Co-fired ceramics (LTCC), various types of such devices have been proposed, such as a point to multi-points communication transceiver with 26 GHz bandwidth, and a short range wireless communication system with 60 GHz and 70 GHz bandwidths.
In such a millimeter wave system, various types of transit structures are used for connecting the transmitters or the receivers to the antennas.
Generally, a conventional transit structure is a micro strip line, or a transit structure of a strip line and a waveguide, by using a single layer substrate technology. A rear side cavity shape is generally required through fabrication of a mechanical structure.
Recently, a transit structure using a stack process has appeared; this is a structure using a dielectric cavity and an aperture with a lowest surface as a dielectric waveguide and another waveguide. In such conventional technology, there are several shortcomings in realizing a structure having an optimum performance, due to a complex matching structure and dielectric resonator, and many parameters the aperture may have.